


Blood Moon's Curse - Growth Drive

by Etherious01



Category: Star vs. The Forces Of Evil
Genre: Corruption, Demon Transformation?, Demon cock, Growth, Growth Drive, Large Cock, M/M, Muscle Growth, Transformation, cock growth, hyper, macro
Language: English
Status: In-Progress
Published: 2019-05-30
Updated: 2019-06-05
Packaged: 2020-03-30 02:33:46
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,106
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19032979
Author URL: https://archiveofourown.org/users/Etherious01/pseuds/Etherious01
Summary: Tom's Dance at the Blood Moon Ball really didn't go as planned, as he knocks Star out of the way to one-up Marco, but his power mixed with the power of the blood-moon creates a pretty powerful mixture. Feelings fly between the two, but the power inside Marco is making him grow... will Tom keep things under control... or better yet, will he keep his pants on!





	1. Chapter 1

**Author's Note:**

  * For [BizarreJoe](https://archiveofourown.org/users/BizarreJoe/gifts).



> Growth Drive for my friend, Bizarrejoe. If you're curious, look here! Going on for 2-3 days!
> 
> https://twitter.com/Etherious01/status/1134233773602533376?s=20

(Note: minor alteration to canon is Marco meets Hekapoo before the Blood Moon happens)

“Stttaaaarrrrrrr!”

The voice whispered among the dancing demons and revelers as the Blood Moon Ball carried on, although everyone was pretty discontent with how this year’s ball had been going. The Prince of the Underworld, Thomas, or Tom as he was frequently called, had taken all the fun stuff out. He’d replaced the usual blood with unicorn blood, dared to invite better looking monsters, and even took the traditional songs out, all so he could dance with Star Butterfly! Of course, no one dared question him since he had quite the temper, although he was apparently trying to keep it in check for this. The only weird thing was the somewhat attractive skull-faced monster darting through their legs to get at her. “Stttarrr, over here!!” He ran over to the Mewni Princess, as he grabbed her hand.

The monsters had to admit she looked beautiful (even those that swung the same way), the Princess’ blonde hair tied in a ponytail behind her, while she wore a long pink dress covered in hearts, the perfect match to the heart marks on her cheeks and her light blue eyes. “How did you know my name?” She asked, as the skull-faced monster grabbed both of her gloved hands. She had to admit, she was almost smitten. (Then again, she was usually smitten with just about every person and monster that approached her).

She didn’t recognize her Hispanic friend since he wasn’t wearing his usual tight pants and red hoodie. He was wearing a Mariachi outfit, with a white button-up and red tie, and he’d covered his face with a skull mask, and his brown hair with a red sombrero, all of them intricately decorated with a golden vine pattern. He didn’t have time to respond though as the lights in the ballroom suddenly went out.

They both looked up at the lunar eye on the ceiling as it opened up, a crimson light falling down onto both of them on the center. A creepy music started playing as they both instinctively started dancing. Marco had to admit, he was glad he took those ballroom dancing lessons for $400. “Star, it’s me!!” He explained, lifting his skull mask up to show his face, mole and all. 

“Marco?!” Star said, completely shocked at her friend. How the heck did he even get here!! They carried on their dance however, smoothly, each of their footsteps somehow in sync with one another. “What are you do- OOF!” Star grunted as she was roughly bumped out of the way, flying across the room into a cauldron of unicorn blood with a splash.

“What the hell do you think you’re doing?!” Marco blinked as someone shoved Star out of the way, taking her place in the dance. He gulped as he saw all three eyes of Tom staring angrily at him, the demon dressed in a white tailcoat, gritting his sharp teeth angrily. The lilac-colored, salmon-haired demon gripped Marco’s hands tightly as he tried to hijack control over the dance. “This dance is supposed to be for Star!!” He hissed, Marco raising a brow at that. 

“Oh really? Then why are you the one dancing with me?” Marco quipped, smiling as Tom hissed further, Marco pushing further back to try to take control back. One thing he could say was that Tom was not nearly as good a dancer as he was. They struggled back and forth, their bodies rubbing against each other almost sensually, unaware of Star nearly drowning in the unicorn blood. Marco had to admit, Tom’s eyeliner for his red eyes, all three of them, was almost kind of cute, bathed in the moon’s light. Once Marco saw his opportunity though, he hooked his leg behind Tom’s ankle, and tripped him up, sending the demon toppling to the ground. “What’s the matter, got two left claws?” He quipped.

“WHY YOU-!!!!!!” Tom roared, his eyes glowing completely red now as he bared his fangs at Marco in a growl, flames starting to build around the entire ballroom as everyone tried to take cover from the intense heat.

“Now now Mr. Tom, there’s no need for things to get out of hand! Keep calm keep calm!” Tom’s self-help coach Brian ran up, panicking. The queen was not going to be happy! “Just focus on the bunny!!” He shouted, holding up Tom’s stress relief bunny. Tom grabbed him by his shirt and threw him to the side.

“I have HAD ENOUGH OF KEEPING MY TEMPER IN CHECK!!” Tom raged, flames shooting all the way up to the very ceiling as he started floating in the air. Marco gulped, hoping Star could help him out of this. Mayyybbee pissing off the demon wasn’t the best choice in the entire planet. “RAWWWWWWWGGGGHHHHHHH!!!!” Tom shrieked, flames shooting all the way through the diadem in the sky of the underworld.

It was cut off though as a blast of cold air flew through the room, Tom crashing to the ground as a frozen block of ice as Star stared at him, the Mewni princess absolutely pissed off and covered in Unicorn blood. “What the hell Tom?!” She shouted, her image only enhanced by the blood moon’s light, making her look even more terrifying than a demon out of hell. Marco gulped. Perhaps he was better off with Tom…

“Hey, what’s that?” Someone said as they looked up, the blood moon’s light starting to spark with demonic energy. Marco looked up and gulped. That really didn’t look good… The energy grew more and more violent before a massive blast of pure demonic power shot down from the Blood Moon… right where Marco was standing…

“Uh oh.” He said, seeing the blast coming right at him. Everyone took cover as the force of energy crashed against the ground, practically frying the poor Karate master. He didn’t have time to even scream as he was bathed in its energy.

“Marco?!” Star screamed, running towards him as he collapsed to the ground, practically charred black. “Are you alright?!” She shouted, holding her friend as he coughed up some smoke, his eyes opening up and glowing slightly red before they returned to their usual brown.

“St-star?” He said, before his eyes rolled back and he lost consciousness. Star panicked and started shaking him violently, hoping it might just wake him up. She wasn’t exactly known for her subtlety after all.

“Well, this is a problem…” Star and everyone turned as a Mewman walked into the ballroom, everyone gasping as they fell to their hands and knees. She was a bit confused. Who was this guy? He was just a Mewman, right? She didn’t see Tom starting to shake so hard in fear the ice encasing him was cracking. “Oh my apologies, I’m Dave Lucitor, Tom’s father and King of the Underworld.”

“Oooohhhhhh…” Star said. Considering how Tom looked, he was… rather unremarkable. A brown-haired, green-eyed man dressed in a royal red tunic, completely with crown. He was practically… normal. Her mind jumped to what he said though. “Wait, a problem though? Is Marco alright?!” She said, running up to him and grabbing him by the tunic. “Is he gonna die?!?!?!”

“Please let go of me.” Dave said, smacking her hands as he dusted his tunic off. “Well, the Blood Moon supposedly links two together, but we’ve never had SOMEONE,” he said, emphasizing the word as he looked to his son encased in the ice, “blast pure demonic power into it as well.” He walked over to the unconscious Marco, rubbing a bit of black soot off of Star’s friend. “That blast was the result of that, so frankly… I have no idea what’s going to happen.” 

He walked over to the ice encasing Tom and snapped his fingers, the block shattering into multiple shards of fine mist. “YOU HOWEVER!” He shouted, making Tom shrink up into a little ball. “ARE GOING TO BE WATCHING OVER HIM! DO YOU UNDERSTAND ME!” Tom shook his head as everyone evacuated. Star kind of understood though where Tom got his temper from though. Dave cleared his throat. “I think it’s best if you head out and keep an eye on your friend, Ms. Butterfly.” He pointed to his son. “Tom will accompany you, and if he gets out of hand, let me know please.” With that, he walked out.

Star turned to Tom who was currently huddled up in a ball, muttering for mercy over and over again, and Marco who was still unconscious. “Well, this was one heck of a party….” Star muttered, holding up her wand as she opened up a portal back to Marco’s house. She paused for a second, looking at everyone who was currently hiding from the King’s rage before smiling. “However…” She said, a evil plan coming to mind as she grabbed Marco and Tom by their legs and threw them into it before shutting it. “WHO’S READY TO HAVE AN ACTUAL PARTY!!” She shouted, jumping to a table as she sent several magical fireworks into the air.

Everyone just looked at one another before smiling, crowding around her and tossing her up into the air repeatedly. “PARTY PARTY PARTY!!!” They cheered, the sounds of their celebration echoing through the entire underworld.

====x====

On the other side of the portal…

“Oh man… why did I have to be stuck with this loser….” Tom groaned, shivering from the cold he was encased in and from fear of his dad. Marco was still out cold though, and still charred. “Damn it!” He growled, grabbing Marco by his foot as he tried to find the guy’s bathroom. “Better get you cleaned up at least….”

To be continued~


	2. 3 Ko-fi: 6 C

**Summary for the Chapter:**

> Hoping to upload 3 ko-fi every 1-2 days~

Marco:  
5’4”  
118 lb  
6 Inches

3 Ko-fi (6C) - 9 - 15 P

*SPLOOSH!*

“GAH!” Marco gasped as he was shocked wide awake, his body impacting against the warm water of some bath. “What the-?!” He shouted, shooting straight up as he coughed, trying to catch his breath as he nearly drowned in a bathtub. His eyes shot around as he tried to get his bearings. Star! Tom! The Blood Moon Ball! Those were the last things he remembered….

‘Wait…’ He looked around as he realized he recognized where he was. He was in his bathroom! The cheesy tile and bathtub big enough to hold two people But how the heck did he get there? Tom was about ready to incinerate him, and then… Star froze him, then something about the Blood Moon? After that, there was a lot of pain, and things went black after that… At least the bath was warm at least. “Just relax…” he sighed, relaxing as he sank into the bath. The warm water felt good at least, Marco almost moaning as he felt his 6 incher reach full hardness.

“Man, why do you humans just soak in water?” Marco paled as he turned, and screamed (totally not high-pitched at all). Tom just flinched as he rubbed his ears, Marco’s scream hurting his sensitive hearing. “Ow, geez, why do you things always have to scream…” He muttered. Part of the reason Marco might’ve been screaming was the fact he wasn’t wearing clothes, showing his lithe frame off as his spaded tail twitched behind him. Also the fact he was letting his dick hang out, and dear God, his softie was easily twice Marco’s hard-on, compete with a pair of softball-sized testicles.

“Geez, so prudish.” He said, shrugging as he ignored Marco’s protests, and stepped inside. “Scootch over, you’re taking up all the space!” Tom chided as he sank in, sighing as the warm water enveloped him, feeling very good against his purple skin. All of his eyes shut as he welcomed the heat, soaking into his muscles and loosening them. “Man, this even feels better than fire!” He sighed, one hand slowly starting to reach down as his penis started hardening, aroused by his pleasure. Marco’s eyes slowly watched as Tom’s cock grew erect under the water, the demon moaning as one hand reached down to grip it, giving it a few strokes. Marco almost couldn’t believe his eyes as he saw the tip of Tom’s cock poke through the water’s surface. Unlike his own cock, Tom didn’t seem to have foreskin, but upper half of his dick was covered in small spiky nubs, probably for maximum pleasure. Tom opened one eye and smirked at Marco as he kept up his stroking. “Like it? A full 15 inches if we use your human measurements?” Marco felt an atomic blush at that; couldn’t help but notice his dick felt strangely warm as well. “How’s yours compare?”

Marco turned redder than his favorite jacket as he reflexively threw his arms in front of him and clenching his legs together. “Th-that’s none of your business!” He stammered, hoping the demon wannabe-boyfriend of Star would drop the topic. Tom just pointed at the bathtub, but Marco had to admit he had a point there. They were already bathing together after all. “S-six…” He admitted a bit defeatedly, reaching down to grip his cock, only to feel a bit more than he remembered. “Wh-what the?!” He stood up rapidly, his dick flopping up against his stomach as he gripped it. He’s used his 6 inches long enough to know it was bigger, and he was probably more than half Tom’s size now, maybe somewhere around 8 inches now?! “I-it’s bigger?!”

Tom wasn’t quite sure what was going on, but Marco seemed freaked, saying it was bigger? His dad did say he didn’t have any idea what was going to happen. He had to admit though, he was liking what he was seeing. Marco was definitely a pretty fit guy, although he had a little bit of stomach pudge. “Heh, I don’t see the problem with that.” He smirked, getting up as well. Demons like him weren’t limited to different sexes for their partners, and he had to admit, tormenting Marco was actually pretty fun. “Definitely what matters is how you can use it.” Tom said, reaching down as he gripped both of their cocks together.

Marco leaned back against the wall as Tom rubbed their cocks together, his uncut cock against Tom’s spined one, moaning as the demon leaned forward. “Wh-what are you doing?” He gasped as Tom stroked his dick off. “St-stop…!” Marco moaned, starting to leak pre over both of them as his dick continued to feel warm, especially under Tom’s infernal touch. He couldn’t help but reach down to join Tom’s stroking, barely noticing his dick had grown another inch as well, now a full 9 inches long, and almost as thick as Tom’s wrist-sized demonhood.

“Oh, getting assertive now!” Tom panted as he felt Marco’s fingers, calloused from years of martial arts rub against his sensitive cock. He looked down, just to make sure he wasn’t imagining it. Marco’s cock was definitely getting bigger. The martial artist couldn’t help but feel a bit of pride as he looked down too, his cock stretching even longer to break double-digits, a literal stretch goal for any guy. Tom was naturally born hung, but to see anyone, even his hated rival growing like this, it was too much for a horny demon just to only see this. “Don’t mind if I do.” He purred, getting to his knees as the water sloshed against them.

“Ungh, s-so good!” Marco gasped, tensing up as the demon gripped his cock tightly, tiny sparks of energy faintly visible as his cock extended another inch, becoming a delicious 11 inches of pure Hispanic dick. It was large enough now that Tom could grip it with both hands and still have some space in between. “AH!” Marco gasped as he strengthened his hold, leaning forward to lick the tip.

“Heh, not bad for a human.” Tom quipped, grinning as he tasted his pre, salty with just a hint of nachos. He could already feel Marco’s cock starting to throb again, and that gave him a fun idea. Eyes glinting, he opened his mouth wide as he took Marco’s cock straight to the hilt, making the teen’s eyes go wide as Tom enveloped his manhood in a warm, moist environment, his tongue tickling the bottom as he slurped away. One hand reached up to tease Marco’s balls while his tail snaked towards his own cock, wrapping around it a few times. “Mmmmm…” Tom moaned as he started bobbing up and down, doing everything he could to please it, just to hear Marco moan.

“C-come on, wh-what if someone sees!” Marco glanced towards the door, afraid to make a sound in case someone came in, that someone being Star in particular. She had no respect for privacy after all. He couldn’t resist though as he rested one hand on Tom’s head, slowly drifting towards one of his horns as he started thrusting into the demon’s mouth. “C-come on…!” He begged, no longer sure if he was asking Tom to stop, or to get him off as he added another hand. Tom’s eyes went wide as Marco gripped him by the horns tightly, shoving his head down deeply onto his cock. Macro grunted as his cock gained yet another inch, reaching a full foot in length, almost unheard of for any guy, Tom gagging as he felt the extra length take up more space in his throat as Marco buried his face at the base of his cock, his pubic hair and musk tickling Tom’s nose. “C-cumming!!”

Tom coughed as he felt Marco’s now apple-sized balls pulse, shooting a thick load down his throat, filling his stomach as he pulled off to avoid choking. Marco tensed up as his hands immediately shot to his cock, stroking it off as he let off several thick streams of cum into the air, landing in his hair, on the side of the tub, on Tom’s face… even after his orgasm died down, Marco was still lost in pure bliss as he tackled his larger cock. “Well, you aren’t gonna hog all the fun, are you?” Tom smirked, catching the flushed Marco’s attention, as he gestured to his own erection. Marco eeped and jumped out of the bathtub, leaving Tom to his own devices, frowning as he left the demon alone. “Oh come on, I suck you off, you could at least return the favor…” He grumbled as he sat back down, both hands and tail wrapping around his cock. “Ungh, wouldn’t hurt to return the favor…!” He moaned, sinking back into the tub as he lost himself in his pleasure.

Marco:  
5’4”  
118 lb  
12 Inches


End file.
